1. Field of the Invention
The present invention relates to an articulated robot. More particularly, the present invention relates to an articulated robot having a multiple of freedom which can be advantageously utilized in an automatic welding apparatus or the like, wherein information is taught in one or two coordinates systems and movement is controlled in an articulated system.
2. Description of the Prior Art
Articulated robots have been heretofore utilized in manipulators or other types of automated machines. One example of such articulated robots is disclosed in Japanese Patent Laying Open Gazette No. 50376/1974. A typical articulated robot comprises at least one arm turnable provided about a given shaft and a second arm rotatably provided about the above described arm. A third arm, a fourth arm and so on are in succession turnably provided and a functional element such as a welding torch, a holder or the like is provided at the end of the last arm. The turning angles of the respective arms are controlled so that the holder, the welding torch and the like are controlled to a desired position, whereupon welding or other processing is performed as necessary.
A conventional articulated robot is adapted such that the first arm and the second arm turnably provided to the first arm can assume one state in which the first arm and the second arm are bent at the journal shaft starting from a predetermined state in which both arms are aligned in a linear manner. Conversely described, a conventional articulated robot was adapted such that a bent state is controllably achieved only in a given one direction. However, assuming that the arms can assume only one state depending on the magnitude or the geometry of workpiece, it could happen that the arm collides with the workpiece. In such a case, the welding torch can not be controlled to such target position, unless a workpiece fixing state or position is changed. Thus, it is extremely tiresome to change the position of the workpiece to avoid collision of the arm and the workpiece in the course of operation of automatic welding and the like, for example.